1. Field of the Invention
The present invention pertains to the field of advanced sporting equipment design and in particular to a golf club head system for a putter, driver, or iron designed for control of spin resulting from impact between the club head and a golf ball through elastically tailoring normal and tangential impact compliance.
2. Background Art
The present invention pertains to achieving an increase in the accuracy and distance of a golf club (e.g., a driver, putter or iron) through the application of structural design techniques and elastic tailoring of the club and in particular to enhancing or diminishing ball spins. There have been many improvements over the years which have had measurable impact on the accuracy and distance which a golfer can achieve. Typical passive performance improvements such as head shape and volume, weight distribution and resulting components of the inertia tensor, face thickness and thickness profile, face curvatures and CG locations, all pertain to the selection of optimum constant physical and material parameters for the golf club.
The impact between the ball and the head can be modeled as an impact between two elastic/deformable bodies each having freedom to translate and rotate in space i.e., full 6 degrees of freedom (DOF) bodies, each having the ability to deform at impact, and each having fully populated mass and inertia tensors. The typical initial condition for this event is a stationary ball and high velocity head impacting the ball at a perhaps eccentric point substantially on or substantially off the face of the club head. The impact results in high forces both normal and tangential to the contact surfaces between the club head and the ball. These forces integrate over time to determine the speed and direction, forming velocity vector and spin vectors of the ball after it leaves the face, hereafter called the impact resultants. These interface forces are determined by many properties including elasticity of the two bodies, material properties and dissipation, surface friction coefficients, body masses and inertia tensors.
The present invention pertains to the design of the elastic structural parameters of the head and in particular the attachment between the head body and the face or face insert such that the impact resultants benefit from the elastic/dynamic response of the clubhead under the impact forces. For example the structural design can be such that the face deflections and dynamic response are selected to maximize or minimize ball spin resulting from the impact. There has been much work in the area of elastic tailoring of a golf club head to influence the impact of the head and the ball and the resulting ball flight.
U.S. Pat. No. 4,498,672 to Bulla issued Feb. 12, 1985 discloses a clubhead designed so that the elastic response of the club in the normal direction is tuned such that it's flexure frequency matches a distortion frequency of the ball. The goal is to increase flight distance by increasing the Coefficient of Restitution (COR).
U.S. Pat. No. 5,299,807 to Hutin issued Apr. 5, 1994 discloses a clubhead designed with a thin visco-elastic sheet sandwiched between a face and a club head for improving impact performance and feel. There's no mention of spin, but the patent describes an elastically supported face.
U.S. Pat. No. 5,316,298 to Hutin issued May 31, 1994 discloses a club head designed with a constrained layer visco-elastic damping treatment mounted on the face and or the body for noise tailoring. There's no mention of spin control or control of impact resultants, but the patent discloses an elastically supported face.
U.S. Pat. No. 5,505,453 to Mack issued Apr. 9, 1996, perhaps the closest to the present invention, discloses several (2) designs for an elastically supported impact plate whose support can be tuned to maximize normal response and exiting ball velocity for a given player. It essentially uses advanced analytical models (1-d) normal impact only to determine the optimal support stiffness in the normal direction to maximize ball velocity after impact. The patent shows two designs each applied to drivers, irons and putters. There's no mention of spin, but the patent discloses an elastically supported face.
U.S. Pat. No. 5,674,132 to Fisher issued Oct. 7, 1997 discloses a club head designed with an elastically tailored face insert designed to have an desired rebound factor and/or feel/hardness. There's no mention of spin, but the patent discloses an elastically tailored face.
U.S. Pat. No. 5,697,855 to Aizawar issued Dec. 16, 1997 discloses a clubhead (iron and driver) designed with an elastically supported face insert designed to have a desired damping factor. There's no mention of spin, but the patent discloses an elastically supported face insert.
U.S. Pat. No. 5,807,190 to Krumme et al. issued Sep. 15, 1998 and U.S. Pat. No. 6,277,033 to Krumme et al. issued Aug. 21, 2001 disclose a clubhead (iron and driver—190, and putter—033) designed with an elastically tailored face comprising a number of pixels each selected for its elastic properties and selectively arranged to give a desired face effect (sweet spot etc). There's no mention of spin, but the patent discloses an elastically tailored face design.
U.S. Pat. No. 6,001,030 to Delaney et al. issued Dec. 14, 1999 discloses a club head, (putter only) designed with a face insert constructed “with controlled compression”, i.e., a rigid face impact plate elastically supported where the support is designed to provide a certain normal motion behavior depending on impact intensity and/or impact location. There is no mention of spin, but the patent discloses an elastically tailored face design.
U.S. Pat. No. 6,302,807 to Rohrer issued Oct. 16, 2001 discloses a golf club head (preferably putter) designed with variable energy absorption. It discloses designs for viscoelastic supported faces constructed to maximize dissipation in ideal hits and lower dissipation in off center miss-hits. There's no mention of spin, but the patent discloses an elastically tailored face design.
U.S. Pat. No. 6,328,661 to Helmstetter et al. issued Dec. 11, 2001 and U.S. Pat. No. 6,478,690 to Helmstetter et al. issued Nov. 12, 2002, “Multiple Material Golf Club Head with a Polymer Insert Base” disclose a golf club head (preferably putter) designed with a polymer face insert of carefully defined hardness and rebound i.e., an elastically tailored insert to effect impact COR and feel.
U.S. Pat. No. 6,332,849 to Beasley et al. issued Dec. 25, 2001, “Golf Club Driver with Gel Support of Face Wall” discloses a golf club head (preferably driver) designed with a viscoelastic member supporting the face and connected between the center of the face and the back of the hollow body of the clubhead.
U.S. Pat. No. 6,354,961 to Allen issued Mar. 12, 2002, “Golf Club Face Flexure Control System” discloses a golf club head (preferably driver) designed with a pneumatic piston/cylinder supporting the face and connected between the center of the face and the back of the hollow body of the clubhead. The piston is designed to make contact and change effective stiffness in a predetermined impact velocity range.
U.S. Pat. No. 6,364,789 to Kosmatka issued Apr. 2, 2002, “Golf Club Head” discloses a golf club head designed with an annular deflection enhancement member disposed between the club head body and a stiff face. The stiffness of the annular member is preferably lower then the face to enhance deflection of the face at impact and increase COR.
U.S. Pat. No. 6,478,693 to Matsunaga et al. issued Nov. 12, 2002, “Golf Club Head” discloses a golf club head (preferably driver or iron) designed with a variable thickness face with step changes in multiple tiered thickness regions. The centroids of the regions are designed and located to maximize the region of uniformity of strike response—i.e., increase the sweet spot under normal impact.
U.S. Pat. No. 6,488,594 to Card et al. issued Dec. 3, 2002, “Putter with a consistent Putting Face” discloses a putter designed with a face insert designed to maximize dissipation in ideal hits and lower dissipation in off center miss-hits. There's no mention of spin, but the patent discloses an elastically tailored face design.
U.S. Pat. No. 6,592,468 to Vincent et al. issued Jul. 15, 2003, “Golf Club Head” discloses a golf club head designed with a viso-elastically supported insert for increasing the damping in vibrations in the club caused by impact.
U.S. Pat. Nos. 6,595,057 and 6,605,007 to Bissonnette et al. issued Jul. 22, 2003 and Aug. 12 2003, respectively, “Golf Club Head with High Coefficient of Restitution” discloses a golf club with a face whose thickness is tailored to maximize COR. The face has a higher stiffness central zone and a lower stiffness surrounding zone.
U.S. Pat. No. 6,602,150 to Kosmatka issued Aug. 5, 2003, “Golf Club Striking Plate with Vibration Attenuation” discloses a golf club with a variable thickness face (thicker central portion) on which is disposed a viscoelastic material for face vibration attenuation.
All of the aforementioned patents deal with clubhead designs such that the elastic response of the head and face during impact impart a benefit to feel and or COR of the clubhead. None of the aforementioned patents has addressed the design of the elastic/dynamic response of the clubhead so as to effect beneficial control of the ball spin. U.S. Pat. No. 5,193,806 to Burkly issued Mar. 16,1993, discloses a clubhead designed with a circular shape contact surface to effect spin control, but does not teach the use of clubhead elastic response to achieve this. The face is assumed to be rigid. Numerous patents have attempted to address spin control through surface treatments of the contacting bodies, but none directly address control of spin by elastic/structural design of the clubhead.